...you could use TCP to reliably download frames that were still in the future with respect to what would be played, and then buffer those locally)

I was mucking around with my network recently, with Netflix playing in the background. Rebooted the router, and to my utter surprise, the stream continued to play uninterrupted for the entire (30+ seconds) time it takes my network stack to reinitialize. I did not realize how aggressively the providers buffer, but it completely papered over the lack of internet service for the window.